onsemi MJD50T4

Overview

MJD50T4 from STMicroelectronics is a high-voltage NPN power transistor in TO-252 (DPAK) surface-mount package, rated for 400 V V_CEO, 1 A I_C, and 15 W P_tot at T_c = 25 °C; designed for robust switching in offline SMPS and audio amplifier output stages.

For engineers reviewing the MJD50T4 datasheet, MJD50T4 pinout, MJD50T4 application, or MJD50T4 equivalent, key selection criteria include V_CEO(sus) = 400 V, h_FE ≥ 30 @ 0.3 A, V_CE(sat) ≤ 1 V @ 1 A/0.2 A, R_thj-case = 8.33 °C/W, and TO-252 thermal performance under pulsed inductive loads.

Technical Context

The MJD50T4 employs Medium Voltage Epitaxial Planar technology to achieve high ruggedness and fast switching with controlled SOA curves. It supports pulsed operation up to 2 A I_CM (t_p < 5 ms) and sustains 400 V in switching mode with I_C = 30 mA.

Its f_T = 10 MHz and h_fe = 25 @ 0.2 A/1 kHz confirm suitability for medium-frequency amplification and hard-switched converters. The device features low C_ob and defined switching times (t_on/t_off) optimized for inductive load commutation.

Key Specifications

Pinout & Package

TO-252 (DPAK) surface-mount package with exposed drain-connected tab for thermal management; 3-terminal configuration optimized for PCB-level heat transfer and automated assembly in tape-and-reel format (suffix "T4").

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN power transistor applications.

Compared with TIP50 and MJD47T4, the MJD50T4 offers superior SMT manufacturability and thermal interface control in compact power stages, while delivering higher minimum h_FE than its PNP counterpart-making it preferred for single-ended switching where gain consistency matters.

Availability

MJD50T4 is available at Aetrix Electronics and suitable for switch mode power supplies, audio amplifiers, general purpose switching, and DC motor control requiring stable component supply and long-term industrial availability.

Supply support for MJD50T4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, microcontrollers, and automotive-grade ICs.

The MJD50T4 belongs to ST's high-voltage bipolar power transistor family, engineered for cost-effective, rugged replacement of legacy through-hole devices in modern SMT power conversion and amplification systems.

FAQ

Is MJD50T4 pin-compatible with TIP50?

No. MJD50T4 uses TO-252 (DPAK) with emitter-base-collector pinout (1-2-3), while TIP50 uses TO-220 with collector-base-emitter order (1-2-3). Physical layout, thermal path, and PCB footprint differ significantly-direct substitution requires board redesign.

What is the maximum recommended continuous collector current at 85°C case temperature?

Derating from 15 W at 25 °C using R_thj-case = 8.33 °C/W gives max P_tot ≈ 7.5 W at T_c = 85 °C. At V_CE(sat) ≈ 1 V, this supports ~7.5 A average I_C only if V_CE remains saturated-but practical continuous I_C is limited to ~0.6–0.7 A to maintain T_j ≤ 150 °C.

Does MJD50T4 require a base resistor when driven by a microcontroller GPIO?

Yes. With h_FE ≥ 30 and required I_B = 0.2 A for 1 A I_C, a typical 3.3 V GPIO cannot drive the base directly. A Darlington stage or logic-level MOSFET driver is needed-or a current-limited base resistor network (e.g., 10 Ω + 100 Ω) for pulsed operation below 100 mA average.

Can MJD50T4 be used in avalanche mode?

No. The datasheet does not specify avalanche energy rating (E_AS) or ruggedness under unclamped inductive switching. Its SOA curves assume external clamping (e.g., RCD snubber or TVS). Operation beyond V_CEO(sus) = 400 V risks irreversible second breakdown.